Cellular Respiration Harvesting Chemical Energy ATP 2009-2010
Ch.8.3 Section Objectives: Compare and contrast cellular respiration and fermentation. Explain how cells obtain energy from cellular respiration.
Burn fuels to make energy combustion making heat energy by burning fuels in one step O fuel 2 (carbohydrates) CO 2 + H 2 O + heat aerobic respiration making ATP energy (& some heat) by burning fuels in many small steps ATP O food 2 (carbohydrates) ATP + CO 2 + H 2 O (+ heat)
Energy needs of life Animals are energy consumers What do we need energy for? synthesis (building for growth) reproduction active transport movement temperature control (making heat)
Where do we get energy? Energy is stored in organic molecules carbohydrates, fats, proteins Animals eat these organic molecules food digest food to get fuels for energy (ATP) raw materials for building more molecules carbohydrates, fats, proteins, nucleic acids ATP
What is energy in biology? ATP Adenosine TriPhosphate Whoa! HOT stuff! 2009-2010
Harvesting energy stored in food Cellular respiration breaking down food to produce ATP in mitochondria using oxygen aerobic respiration usually digesting glucose food ATP but could be other sugars, fats, or proteins O 2 glucose + oxygen energy + carbon + water dioxide C 6 H 12 O 6 + 6O 2 ATP + 6CO 2 + 6H 2 O
What do we need to make energy? The Furnace for making energy mitochondria Fuel food: carbohydrates, fats, proteins Helpers oxygen enzymes Product ATP Waste products carbon dioxide then used by plants water food O 2 enzymes Make ATP! Make ATP! All I do all day And no one even notices! ATP CO 2 H2 O
Mitochondria are everywhere!! animal cells plant cells
Using ATP to do work? Can t store ATP too unstable only used in cell that produces it only short term energy storage carbohydrates & fats are long term energy storage Whoa! Pass me the glucose & oxygen! ATP Adenosine TriPhosphate Adenosine DiPhosphate ADP work A working muscle recycles over 10 million ATPs per second
A Body s Energy Budget eat food 1 2 make energy ATP synthesis (building) { energy needed even at rest activity temperature control { growth reproduction repair 3 storage { glycogen (animal starch) fat
Cellular Respiration The first stage, glycolysis, is anaerobic no oxygen is required. The last two stages are aerobic and require oxygen to be completed. SUMMARY EQUATION:
STAGES OF CELLULAR RESPIRATION Respiration occurs in three main stages GLYCOLYSIS High-energy electrons carried by NADH KREBS CYCLE ELECTRON TRANSPORT CHAIN Cytoplasmic fluid Mitochondrion
Glycolysis [Glyco=sweet, sugar lysis = to split] s: a series of chemical reactions in the cytoplasm of a cell that break down glucose, a six-carbon compound, into two molecules of pyruvic acid, a three-carbon compound produces only two ATP molecules for each glucose molecule broken down. (4-2=2) 2 molecules of NADH are formed 4ATP 2AT P 2ADP 4ADP + 4P Glucose 2NAD + 2 Pyruvic acid 2NADH + 2H+
Transition Phase. Before citric acid cycle and electron transport chain can begin, pyruvic acid undergoes a series of reactions in which it gives off a molecule of CO 2 and combines with a molecule called coenzyme A to form acetyl- CoA. Pyruvic acid Acetyl CoA (acetyl coenzyme A) CO2
The citric acid cycle also called the Krebs cycle, is a series of chemical reactions in that the molecule used in the first reaction is also one of the end products. For every turn of the cycle, one molecule of ATP and two molecules of carbon dioxide, 3 NADH, 1 FADH2 are produced. For a total of 2ATP,6 NADH,& 2 FADH2 CO2 Occurs in mitochondrial matrix
The electron transport chain In the electron transport chain, the carrier molecules NADH and FADH 2 gives up electrons that pass through a series of reactions. Oxygen is the final electron acceptor forming water. This sets up a H+ (proton) gradient Allow the protons to flow through ATP synthase which synthesizes ATP (ADP + Pi = ATP) the electron transport chain adds 32 ATP molecules to the four already produced during glycolysis & citric acid cycle Occurs in the inner mitochondrial membrane occurs
What if oxygen is missing? No oxygen available = can t complete aerobic respiration Anaerobic respiration also known as fermentation alcohol fermentation lactic acid fermentation no oxygen or no mitochondria (bacteria) can only make very little ATP large animals cannot survive O 2 yeast bacteria
Anaerobic Respiration Fermentation alcohol fermentation O 2 yeast glucose ATP + CO 2 + alcohol make beer, wine, bread lactic acid fermentation bacteria, animals glucose ATP + lactic acid bacteria make yogurt animals feel muscle fatigue Tastes good but not enough energy for me!
Alcoholic fermentation glucose -> pyruvic acid-> alcohol + 2 CO2 2ATP GLYCOLYSIS FERMENTATION 2 ethyl used by yeast cells and some bacteria to produce CO 2 and ethyl alcohol
Lactic acid fermentation Glucose->pyruvic acid -> 2ATP GLYCOLYSIS 2 lactic acid FERMENTATION used to make cheese and yogurt ~ in humans during strenuous exercise not enough oxygen from blood oxygen debt ~ lactic acid accumulates in muscle; leads to fatigue and pain Will be converted back to pyruvic acid in liver
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